A corn-gobbling pest is appearing in Iowa fields for the first time this fall, leaving some farmers stumped as to how to fight it.
Dr. Matt O’Neal, an entomologist at Iowa State University, says the western bean cutworm may have “bean” in its name, but the insects thrive on munching corn by the ear. For corn growers in Iowa, O’Neal says the western bean cutworm has replaced the European corn borer as the number-one pest. “The moths fly into the state and lay their eggs. The caterpillars, the immature stages, feed on the ears and do extensive damage, damaging the ears and reducing yield,” O’Neil says.
He says the cutworms have been found before as far east as Illinois, Indiana and Wisconsin, but now “heavy flights” of the moths are being reported over Iowa and Nebraska. Farmers who find a few of the worms this year may be faced with a much larger problem next year. “Our website has recommendations for growers as to what level of abundance is high enough to merit the use of some kind of management program,” O’Neil says.
In fields with non-BT corn hybrids, researchers are seeing as much as 70 to 90-percent ear infestation, with an average of two-to-three-percent yield loss in those fields. He says if you already have bean cutworms in your crops this year, there’s no defense. The best bet, according to O’Neil, is to plan ahead for next year.
O’Neal says two varieties of genetically-modified corn are out there from competing companies, one of them protects against the western beat cutworms, the other does not. He says farmers that are seeing infestations may want to keep that in mind when buying their seed for next year’s planting. The university’s website has pictures of the worms and more information about the pests — “www.ent.iastate.edu/trap/westernbeancutworm”.
Related web sites:
ISU website on western bean cutworm